Grinding mill



Aug. 24, 1937. J. MURSCH GRINDING MILL Filed Dec. 25, 1935 s Sheets-Sheet 1 FIG.

FIG.2

to Q 3 Z INVENTOR ATTORNEYS Aug. 24, 1937. J. MURSCH GRINDING MILL 01160 Dec. 25, 1935 3 Sheefis-Sheet 2 INVENTOR ATTORNEYS Patented Aug. 24, 1937 UNITED STATES PATENT OFFICE;

Claims.

This invention relates to a grinding mill of the type using rotating hammers where either the hammers themselves or the links carrying at their outer extremities the separate hammer ends are swingingly or pivotally mounted upon the carrying disks or other carrying members.

In these grinding mills it has heretofore been common to swingingly mount elongated hammers or to swingingly mount the hammer assemblies so that if a hammer strikes an obstruction in the mill, the hammer or the hammer assemblies may swing backward to relieve the tension and to al-- low the hammer to pass the obstacle without damaging the machine. It has been recognized, however, that these swingingly carried hammers have several serious disadvantages in practice. One disadvantage is that when a hammer or a hammer carrying link has been swung back from its usual radiating position, due to meeting a greater obstacle than usual, this deflection of the hammer puts all of the rapidly rotating mechanism of the grinding mill out of balance through there being temporarily more weight and more centrifugal force on one side of the shaft than on the other with a resulting strain and consequent vibration in the machine. Another disadvantage of the independently mounted swingingly supported hammers or hammer links is that when the machine is stopped, all of the hammers swing downwardly on their pivots due to the weight of the hammers. This swinging of all the hammers to one side continues for an appreciable space of time after the machine is placed in motion and during such displacement the rotating parts of the grinding mill are obviously in badly unbalanced condition actually by weight and also as to centrifugal tension. This out-of-balance condition as the machine is being gotten under headway continues until the rotating parts have acquired momentumsufiicient to cause the centrifugal force so generated to bring the swingingly mounted hammers out to a radiating position.

This general out-of-balance condition of all of the swinging hammers which occurs when the machine has been stopped and is being started puts a serious strain and vibration upon the machine and I have found also greatly adds to the starting load upon the electric motor or other motive power as compared to the normal operation of the machine and even as compared to the power required to start a machine where the hammers are in balanced condition from the very beginning (c1. se -11) it has heretofore been impracticable to slowly operate a grinding mill of the type indicated. In grinding many materials it is highly desirable not to have the hammers strike the material with the force and speed at which a grinding mill of the swingingly mounted hammer type must be operated. .In fact, to avoid damaging material and sometimes to avoid setting fire to, or exploding material, it is imperative to keep the grinding members from striking the material so fast or with such speed.

It is the main purpose of my present invention to overcome the several disadvantages above mentioned and to provide a grinding mill of the swinging hammer type wherein the swinging hammers of a pair or series of hammers are automatically counterbalanced by means co-operatively connecting the hammers of said pair or series of h'ammers so that when one hammer is deflected, its co-operating member or members will be correspondingly and proportionately deflected so that said pair or series will not be out of balance whether the machine is-stopped or in rapid or slow motion, and further so that when the machine is stopped all of the hammers of a pair or series of hammers in the machine will be in balanced condition and the hammers of the difierent pairs or series and the hammers of all of the series in a machine will be in balance. In other Words, one purpose of this invention is to so co-operatively connect the swinging hammers of a pair or series of hammers as to at all times hold said hammers automatically incounterbalanced condition both as to static relation and centrifugal relation so that the machine will not get out of balance when being stopped, will not get into unbalanced condition when it has stopped, and will be in perfect counterbalanced condition from the instant of imparting rotative motion to the hammers of the machine whereby the strain and tension and waste of power incident to an unbalanced machine being started is avoided.

A further purpose of this invention is to provide a grinding mill of the swinging hammer type wherein the hammers of the pairs or series are all automatically held in counterbalanced condition and will remain in that condition no matter how slowly or rapidly the hammers are rotated so that I am able to provide a machine which will not only satisfactorily operate at a rapid rate of speed in rotation, but it will satisfactorily operate without waste of power, vibration, or machine strain at as slow a rate of speed as is desired or found necessary for any particular material.

A further purpose of my invention is to provide a machine wherein the hammers of a pair I or Set may be co-operatively connected either positively or resiliently. Where the co-operathaps partly by returning the first hammer towards normal position. A still further purpose of this invention is to apply my aforementioned feature of automatically counterbalancing swinging hammers to types of grinding mill where the grinding may be accomplished in part or wholly by crowding, pushing, or rolling the material to be broken up against the screen or breaker members, of the mill.

Further purposes and advantages of this invention will appear in the specification and claims hereinafter set forth.

While my invention is in the main illustrated and described as applied to a grinding mill where the hammers are co-operatively counterbalanced in pairs, it is within the scope of my invention to so co-operatively connect a set of three or more hammers by spacing them equally about the circle and connecting them all to a common equalizer.

Fig. 1 is a vertical sectional view on line l-| of Fig. 2, illustrating one form of a grinding mill embodying this invention. v

Fig. 2 is a vertical sectional view on line 2-2 Of Fig. 1. M

Fig. 3 is a side elevation of only one pair of hammers with their co-operatively connecting means as shown in Fig. 1 and the immediately adjacent part of a disk, and, in section, the shaf and two pivot rods.

Fig. 4 is a sectional view similar to Fig. 1 but of only the rotating parts and with alleight hammers shown and extended radially.

Fig. 5 is a diagrammatic view of the moving parts of a hammer mill as heretofore constructed and in motion showing four independently swinging hammers with three in radial position and one hammer deflected or swung from radial position.

Fig. 6 is a diagrammatic view of the moving parts of a hammer mill as heretofore constructed; viz, of the independently swinging hammer type and having eight swinging hammers, all swung downwardly in the position they occupy when the machine is not in operation.

Fig. 7 is a side elevation similar to Fig. 3'of one pair of hammers and their co-operatively connecting means illustrating a modified form of my invention.

Fig. 8 is a side elevation similar to Fig. 7 but illustrating another modification of my invention and one wherein the means connecting a pair of hammers effects a resilient connection.

Fig. 9 is a side elevation of a unit of hammercarrying links and separate hammers where the links are co-operatively connected pursuant to this invention to hold the unit in counterbalanced condition.

Fig. 10 is a sectional view on line Ill-l of Fig 9 of the parts shown in Fig. 9.

Fig. 11 is a view showing my invention applied to a set of three hammers.

Referring to the drawings in a more particular description, it will be seen that the grinding mill illustrated includes opposite lower housing members l0 and i I. a semi-circular perforated screen l2 supported by said housing members, an upper front breaker plate l3 at the right hand side of the machine as shown in Fig. 1 and an upper rear breaker plate I4 opposite thereto and having its upper end spaced from the upper part of the .front plate l3 so as to provide the usual feed opening l5, into which the material to be operated upon is directed from the feed table or chute IS.

The semi-circular screen I2 is conveniently held in place between the lower housing mem-- bers l0 and I l by means of internal and external flanges I! and I8 respectively which engage the inside and outside of said screen at its opposite edges. Similar or equivalent means are used to "hold in place the front and rear breaker plates l3 and H. The lower housing members conveniently extend down for some distance below the perforated screen thereby forming a chamber IQ for the ground material that has come through the screen. The material is taken from this chamber IS in any of the conventional ways well understood in the art and so not requiring more definite description herein.

-In suitable bearings 20 and 2| provided upon the opposite housing members l0 and I I there is revolubly mounted the shaft 22, suitably rotated by power such as by a belt applied to the pulley 23 upon one projected end of said shaft.

In the space between the housing members there is mounted upon the shaft 22 the desired number of disks 24 and fixed to rotate with the shaft as by being keyed thereto. These disks are spaced apart conveniently by spacer rings 25 keyed to the shaft. Lock nuts 26 engage threaded portions on the shaft immediately outside of the two end or outsidedisks 24.

At intervals in a circle spaced out from the shaft 22 and the spacer rings 25, the disks are pierced by a plurality of pivot rods 21. These rods are parallel to the shaft and conveniently extend through the whole set of disks 24. In practice, and most conveniently, the rods are arranged in pairs with the members of each pair on opposite sides of the shaft and in -a direct line passing through the axis of the shaft. For purpose of definiteness in description and for illustrating the machine it will be seen that the drawings show disks 24 pierced by 8, pivot rods 21 and providing 4 spaces between the spaced disks, and that in each space between adjacent disks are mounted on opposite pivot rods 21 two hammers. As this machine is illustrated, the hammers 28 and 28' are mounted in the first space counting from the right hand side of Fig. 2 on the uppermost and lowermost pivoting rods 21 and the two hammers 28 and 28 are mount-,

ed in the second space but upon the rods 21 that show in Fig. 1 farthest to the right and farthestto the left respectively. It will be understood that another pair of hammers will be mounted in the third space and these must be oppositely arranged and conveniently will be arranged on two opposite rods not already carrying any hammers, and still a fourth pair of hammers will be mounted in the fourth space on opposite rods and preferably upon the rods not already supporting any hammers. of clearness in the drawings, neither the third nor the fourth pair of hammers are illustrated in Figs. 1 and 2.

The hammers 28 are provided towards their inner ends with a circular hole 29 whereby the hammers are mounted upon the pivot rods 21 and may freely swing or rotate on said pivot rods. In this embodiment of my invention the inner For the sake' ends of the hammers are provided with spaced teeth 30 arranged in a semicircle about the center of the hole 29 and facing outwardly therefrom. That is the teeth, as appears in Figs. 1

and 3 *are extended about the .periphery of this end of the hammer and are conveniently formed by stamping, casting or otherwise as by cutting away the materialbetween the teeth.

The hammers of each pair are operatively connected by an equalizer 3| which in this embodiment of my invention consists of a gear wheel having at its periphery outwardly projecting teeth 32 adapted to intermesh with the teeth 30 upon the inner ends of the hammers. This equalizer 3| is mounted upon the spacer ring 25 already described as occupying part of the space between adjacent disks 24. The periphery of the spacer ring forms the bearing upon which the equalizer 3| may freely rotate. The equalizer gears 3| and hammers 28 are preferably formed slightly thinner than the spacer rings 25 and so thinner than the spaces left between adjacent disks to the end that the hammers and equalizer gear may freely rotate without binding upon the adjacent disks 24. It will be understood of course that each pair of hammers is operatively connected by a spacer gear 3|.

It will now be seen that each pair of hammers in this machine is separately and positively connected by an equalizer gear 3|, and that this cooperative connection of the hammers of a pair will not interrupt or interfere with the usual rotation of all of the sets of hammers by the shaft 22 and the disks 24 and pivot rods 21. normal rotation of the hammers the centrifugal power will keep the hammers of a pair extended radially out from the axis of the shaft in the position of hammers 28 and 28 in Fig. 1. As this machine is organized the hammers rotate in an anti-clockwise direction. As the lower hammer 28 strikes an obstacle in the material to be ground the free end of said hammer will tend to swing back relatively to a radius extending through the axis of its pivot or to swing to the left shown in Fig. 1. It will be obvious on account of the intermeshing of, the teeth of hammer 28 with the teeth of equalizer 3| that the said equalizer will tend to relatively rotate in an anti-clockwise direction and thereby the teeth at the upper side of the equalizer being in mesh with the teeth on hammer 28 will tend to swing said hammer 28 in a clockwise direction relative to its pivot rod. In other words, the 'swinging of the free end of hammer 28 to the left will force a movement of the swinging end of hammer 28 to the right to a similar extent. In Fig. 1 the second pair of hammers 28 and 28 are shown in such a deflected position, due to one hammer. say hammer 28 having engaged an obstacle that made suflicient resistance to turn back the swinging end of that hammer or more properly to hold the free end of said hammer from advancing in a radially extending line passing through the axis of the pivot rod of hammer 28 and the axis of the shaft. Due to the co-operating connection between the ham mers 28 and 28 hammer 28 was relatively turned back on the axis of its pivot at the same time and to a like extent but in a reversed direction. By reversed direction here I mean that as the hammer 28 was apparently swung down by the obstacle it met its companion hammer 28 was swung upwardly. In the same way as already explained, a swinging of the hammer Mi to the left would cause a swinging of ham- During mer 28 to the right. This co-operative connection between the hammers of a pair will in effect add to. the power of any hammer when it strikes an obstacle and the obstacle will have to not only. relatively swing back the hammer striking the obstacle, but also will have to similarly turn back or deflect the other hammer of the pair. While the power of the hammers is thus doubled as against an obstacle the hammers can still be deflected or turned backward freely enough to avoid damaging the machine.

'When one hammer of a pair is turned back through meeting an obstacle, the said hammer and its co-operatively connected hammer come more or less to the position of hammers 28 and 28 in Fig. l, and these deflected hammers will be in counter-balanced condition. In other words, the corresponding deflection of a pair of hammers will always insure that the hammers on opposite sides of the machine are in balanced condition both as to weight and also as to centrifugal power because a deflected hammer on one side will always have a similarly deflected hammer on the other side of the circle of the machine.

In Fig. 3 there is shown a side elevation of only one pair of hammers with their co-operatively 'connecting means; that is, the equalizing gear 3i and with only enough of the other parts of the machine such as the shaft 22, two pivot rods 21. and a part of one of the adjacent disks 24 so as to show the automatic counterbalancing connection between'this pair of hammers.

Fig. 4 is a sectional view similar to Fig. 1, showing only the rotating parts of the machine as shown in Fig. 1 but with all eight hammers shown in extended or radial position, which is the positicn that even my co-operatively connected hammers will assume when the machine is in operation unless one or more hammer and its or their connected hammers has been deflected through an obstacle having met one hammer of any pair as hereinbefore described. This directly radiating position of all of the hammers is also the position the hammers in a machine embodying my invention would assume when the machine was stopped. In other words, when a machine embodying my invention is stopped, the counterbalanced hammers in theory and often in practice would stay all severally extended in a radiating position and so the machine would be in perfectly balanced condition. If, due to slight variation in the weight of oppositely disposed hammers, the heavier hammer tipped downwardly it would turn its co-operatively connected hammerupwardly to a similar extent and so the machine would be in balance when it was again started. The counterbalanced situation of my hammers either as shown in Fig. 1 or Fig. 4 is in marked contrast to the badly unbalanced condition the independently mounted hammers of former machines have assumed when machine was stopped.

Figure 6 is a diagrammatic view of the moving parts of a hammer mill of the independently swinging hammer type as heretofore made when the machine is stopped. In the machine shown in Fig. 6 the hammers 33 are independently swingingly mounted at their inner ends upon pivot rods 34 projecting through a series of disks 35 which are fixed upon the rotated shaft 36. In other words, the machine shown in Fig. 6 is in general construction like my machine shown in Figs. 1, 2, 3, and 4 except that the machine shown in Fig. 6 has no means co-operatively connecting and counter-balancing the pairs or sets of hammers. It will be seen from inspection of Fig. 6 that due to the dropping of all of the hammers of the machine to as nearly a straight downward position as possible the machine there shown will be badly unbalanced each time it is stopped and will remain bady unbalanced for a considerable time after the machine is started. One of the main objects of my invention is to overcome this greatly unbalanced condition of swinging hammers when the machine is first started.

In Fig. there is shown a diagrammatic representation of a hammer mill having disks 35, pivot rods 34* and four independently swinging hammers 33* where one hammer has been deflected due to striking an obstacle. It will be seen that the machine illustrated in this view is out of balance due to having. much more weight and centrifugal tension on one side of a diagonal line than the other, and that this machine will remain out of balance until the centrifugal power gradually draws the deflected hammer outwardly. This condition is in marked contrast to the counterbalanced condition of the four hammers shown in my machine in Fig. 1 where a deflection of one hammer has'turned its oppositely disposed and co-operating hammerto a counterbalanced position. It will be understood of course that after my machine has had some of its hammers come to a deflected position as shown in Fig. 1 these deflected hammers will re- Gil turn to normal radiating posit-ion due to the centrifugal action of the rapidly rotating parts, but during all the interval of the deflected hammers returning to normal directly radiating position the said unit. of the machine or the cooperating pairs of hammers and the machine as a whole will be in counterbalanced position because the two deflected co-operatively connected hammers will in all positions of the said connected hammers be in counterbalanced position due to the said hammers being operatively connected to cause equal motion of the said hammers both on the deflection and on the return from deflection.

Fig. '7 is a side elevation of a unit of a machine embodying my invention in a modified form. In this modified form, instead of several teeth and intervening notches on both the equalizer and the inner end of the hammers, there is provided only one tooth or projection and one indentation or notch on the corresponding intermeshing parts. In this form of my machine the shaft 31, spacer ring 33, spaced disks 39 and the pivoting rods 40 are all the same as the corresponding parts shown in Figs. 1 to 4, but in the machine of Fig. '7 the inner ends of the hammers 4| are provided with laterally projecting bosses 42 preferably circular in side elevation,

and the stabilizer 43 is provided with two oppositely disposed inwardly extending U-shaped recesses or notches 44, adapted to swingingly receive the bosses 42 of hammers 4|. In this construction the hammers 4| and the stabilizer 43 overlap, allowing the laterally projecting bosses 42 to project into the U-shaped recesses 44. It will be understood that the notches 44 are deep enough to allow a considerable swinging of the hammers 4i on their pivot rods 40 and in fact to allow as much swinging action as the hammers will ever be called upon to make without the bosses becoming disengaged from the recesses 44. It will be seen that in effect this intermeshing of the bosses upon the hammers with the stabilizer is a mechanical equivalent of the full set of teeth on the equalizer gear 3|, and the semicircular sets of teeth 3|! upon the hammers 28. In this modification also the hammers of a set will at all times be held in counterbalanced condition automatically.

Fig. 8 shows a further modification of my invention in that in this construction the means co-operatively connecting the oppositely disposed hammers 45 include'resilient means whereby a forced deflection of one hammer is not instantaneously and fully transmitted to the other hammer, but a yielding connection is provided which absorbs part of the shock of the deflection of the first hammer, and then gradually transmits the deflection to the other hammer. In the form of this resilient connection shown in Fig. 8 the equalizer 46 has secured to its outer periphery two oppositely disposed bow-shaped springs 41. The circle of each bow flts a portion of the equalizer 46 and is secured thereto by screws 48. The projected ends 41- of these spring members are spaced apart on each side of the machine sufliciently to receive therebetween the ears 43 provided upon the inner ends of the hammers 45. In this construction it will be understood of course that the hammers 45 are swingingly mounted near their inner ends upon pivot rods 50 projecting through two or more of the rotated disks 5|, said disks being mounted upon the shaft 52 and rotated thereby as by a proper key. In this construction also preferably I used the spacer rings 53 to hold the disks apart and to provide a bearing for the equalizer 46. Assuming that the left hand hammer of this Fig. 8 strikes an obstacle which deflects said hammer upwardly the ear 49 of this hammer will travel downward relative to the pivot rod 50 carrying said hammer and will exert its power in the first place upon the left hand projecting end 41 of the lower spring 41. The construction of said spring 41 is such as to allow the left hand arm or end 41* to bend slightly, thus somewhat cushioning the positive action of the ear 4!! of the left hand hammer '45. The spring action, however, of this left hand end of the lower spring 41 will at once tend to rotate the equalizer in an anti-clockwise direction. This tendency to rotate will be partly absorbed by the bending under spring action of the right hand arm 41 of the lower spring 41 coming into engagement with the ear 49 upon the right hand hammer 45. The directly upward rotation of the right hand arm 41* of the lower spring 41 would of course tend to swing the outer end of right hand hammer 45 downwardly against the centrifugal action of said hammer 45. It will thus be seen that the spring action or resilient means provided in. this construction ultimately moves the connected hammer to counterbalancing position and will thereafter hold the hammer in counterbalanced condition until they gradually but'concurrently come back to normal radiating position.

Referring to the modification illustrated in Figs. 9 and 10, it will be seen that the fixed parts of the machine are the same as illustrated in Figs. 1, 2 and 3 and already described in detail and that-the shaft 54, the. spacer rings 55 and toothed equalizers 55 are the same as the corresponding parts' 22, 25 and 3| 'in the machine shown in Figs. 1, 2 and 3. The hammers in this modification however dififer from those first described in connection with Figs. 1 to 3 and also are used two-piece hammers or hammer assem-- blies consisting of the hammer link 51 and an extra part or separate hammer end either in the form of a disk 58 or an irregular or angular shaped hammer end 59. The hammer links 51 are provided with holes 60 near their inner ends whereby the hammer links and thereby each separate hammer assembly is pivotally mounted upon its pivot rod 6| which pivot rods in turn are carried as heretofore described with other forms of the machine by the plurality of large disks 62. The periphery of the inner end of each hammer link 51 is provided with radially arranged teeth 63 intermeshing with similarly arranged teeth 54 upon the equalizers 56 so that when either hammer link 51 of the pair of such links co-operatively connected to one equalizer 58 is deflected the other hammer link of the pair will be correspondingly deflected, re-

sulting in the cooperative connection and the counterbalanced result heretofore described in detail with other forms of my machine. The separate hammer disk 58 or hammer ends 59 are pivotally mounted upon their respective hammer links 5! as by said members 58 or 59 being provided with a hole therethrough rotatively fitting a pivot pin or bolt 65. As these members whether disks or angular ends are pivotally mounted upon the outer ends of the hammer links 57, it will be seen that they will rotate more or less closely to the screen l2 and will have considerable of a rolling and pushing or pressing action upon the material being handled by the material. It will be obvious that these separate hammer ends may be all disks 53 or all angular shaped ends as the parts 59 or that other more irregular shaped separate hammer ends may be used or any combination thereof. It is obvious from the illustration and explanation already made that each pair of hammer assemblies operatively connected by a toothed equalizer 56 will always be in counterbalanced position not only when the hammer assemblies are extended radially in normal running position, but when any one of the hammer assemblies has been defiected by meeting an obstacle or by having come to' other than a direct radiating position clue to the stopping of the machine as heretofore mentioned.

Fig. 11 is a detailed view similar to Fig. 3 but illustrating a further modification of that form of my machine wherein instead of simply a pair of hammers ,there is used a set of three hammers 66. These hammers are co-operatively connected together through all of them intermeshing with the equalizer 61 rotatably mounted upon the ring 68 carried on the main shaft 69. All of,the hammers 66 of this set of three are of course carried in the space between two adjoining hammer-carrying disks I0 and are pivotally mounted on three rods H which are .equally spaced about the circle and of course are spaced an equal distance out from the axis of the shaft 69. This modification illustrates the feature that my invention isnot limited to co-operatively connecting simply a pair of hammers in counterbalanced condition but may be used to hold a set of three or more hammers in such situation. As long as these hammers are mounted on pivot rods equally spaced apart, the hammers will be in balanced situation as to direct' weight and also as to centrifugal tension in any condition of the machine.

What I claim as new and desire to secure by Letters Patent is:

1. In a grinding mill, the combination of a set of rotated hammer-carriers, including pairs of oppositely disposed pivots spaced out from the axis of said carriers, hammers respectively mounted near their inner ends on said pivots and means including resilient members co-operatively connecting the hammers of each pair for like movement on their pivots whereby on swinging motion of either hammer on its pivot a like swinging motion is imparted to the other hammer of the pair.

2. In a grinding mill, the combination of a set of rotated hammer-carriers, including pairs of oppositely disposed pivots spaced equally from the axis of said carriers, hammers respectively mounted near their inner ends on said pivots and having projections at their inner ends and for each pair of hammers a separate equalizer revolubly mounted on the axis of said hammer carriers having at its opposite sides arms havinga resilient action and intermeshingly engaging the said projections of a pair of hammers whereby whereby on swinging motion of any hammer on its pivot a like swinging motion is imparted to the other hammer or hammers of said set.

4. In a grinding mill, the combination of a plurality of rotated hammer-carriers, including pairs of oppositely disposed pivots spaced equally from the axis of said carriers, hammers arranged in independent pairs and respectively mounted near'their inner ends on said pivots and having projections at their inner ends and for each pair of hammers a separate equalizer revolubly mounted on the axis of said hammer carriers and interengaging at its'opposite sides said projections at the inner ends of its pair of hammers whereby all the hammers connected to an equalizer are co-operatively connected for automatic counterbalanced like movement on their pivots and independent of any movement of the hamcarriers and having parts intermeshingly engaging the inner ends of the hammers of that set for co-operatively connecting the hammers of that set for like movement on their pivots when one hammer of the set is moved whereby all the hammers of the respective sets are held in counterbalanced position when the mill is operating at any speed and when the mill is not operating.

JonN mason. 

